反應燒結法製備A4Nb2O9 (A=Mg,Ni)微波介電陶瓷之研究

Preparation of A4Nb2O9 (A=Mg,Ni) Microwave Dielectric Ceramics by Reaction-Sintering Process

蔡宗憲(Zong-Sian Tsai)

指導教授 ： 劉依政

崑山科技大學/工程學院/電子工程研究所/碩士(2012年)

https://doi.org/10.6828/KSU.2012.00073

摘要

本研究以反應燒結法製備Mg4Nb2O9 (MN) 與Ni4Nb2O9 (NN) 微波介電陶瓷。原料粉末混合後未經煆燒，直接成型並燒結。另外混合CaTiO3與 SrTiO3之0.5Mg4Nb2O9-0.5CaTiO3 (MNCT) 與0.6Mg4Nb2O9-0.4CaTiO3 (MNST) 陶瓷體，來修正共振頻率溫度係數(τf)趨近於0 ppm/oC。添加過量Mg(OH)2來製備單一生成相MN陶瓷體，並分別對生成相、微結構及微波介電等特性進行研究。MN陶瓷在X光繞射(XRD)分析中，燒結2小時可發現，其主要生成相為Mg4Nb2O9，並有少量次要相MgNb2O6 生成，當燒結溫度在1200oC會生成次要相Mg0.652Nb0.598O2.25。在1300oC燒結6小時可得到最佳密度4.26g/cm3，收縮率為21.92%。1170oC燒結2小時最佳微波介電特性εr為10.74，Q×f＝231,368GHz(12.18GHz)，τf ＝－40.24ppm/oC。MNCT和MNST陶瓷在1225-1325oC燒結2小時， 分別生成Mg4Nb2O9和CaTiO3 與SrTiO3混合相。其中τf分別為－6.55與－18.21ppm/oC。MNH5陶瓷XRD分析中，其生成相為Mg4Nb2O9單一相，並無次要相生成，可成功製備出MN陶瓷，在1300oC燒結2小時可得到最佳密度4.14g/cm3達理論密度值約94%，收縮率為23.67%，1170oC燒結4小時最佳微波介電特性εr為10.37，Q×f＝203,620GHz(12.68GHz)，τf ＝－20.81ppm/oC。NN陶瓷在1170oC到1300oC燒結2小時，可獲得主要生成相為NiNb2O6，並有少量未反應NiO存在，在1300oC燒結，會開始出現Ni4Nb2O9次要相，燒結溫度大於1300oC時，主要生成相會轉變為Ni4Nb2O9，並且次要相NiO幾乎不存在，可獲得Ni4Nb2O9純相。在1350oC燒結2小時可得到密度5.71g/cm3達理論密度值96.3%，收縮率為13.97%。最佳微波介電特性εr為13.23，Q×f＝21,085GHz(10.53GHz)，τf ＝－13.58ppm/oC。另外，溫升/溫降為30oC/min之NN陶瓷，在1300oC燒結2小時，主要生成相為Ni4Nb2O9純相，此證明溫升/溫降速率會影響Ni4Nb2O9生成相。

關鍵字

反應燒結法 ； 微波介電陶瓷

並列摘要

Microwave dielectric ceramics Mg4Nb2O9 (MN) and Ni4Nb2O9 (NN) prepared by a reaction-sintering process were investigated. The mixture of raw materials was pressed and sintered into ceramics without any calcination stage involved. CaTiO3 and SrTiO3 were used to obtain MN with near-zero τf. Single-phase MN ceramics were obtained by adding excess Mg(OH)2. Mg4Nb2O9 along with minor MgNb2O6 were found in 2h sintering MN. Mg0.652Nb0.598O2.25 phase appeared at 1200oC sintering. The optimum density 4.26g/cm3 and shrinkage 21.92% were obtained at 1300oC/6h sintering. εr＝10.74,Qxf＝231,368GHz(12.18GHz),τf＝－40.24 ppm/oC were obtained at 1170oC/2h. MNCT and MNST ceramics were composed of Mg4Nb2O9 with CaTiO3 and SrTiO3,respectively. MNCT with τf＝－6.55 and MNST with τf＝－18.21ppm/oC were obtained. MNH5 ceramics with single-phase Mg4Nb2O9 could be obtained and no second phase was detected. The optimum density 4.14g/cm3 and shrinkage 23.67% were obtained at 1300oC/2h sintering. εr＝10.37,Qxf ＝203,620GHz (12.68GHz),τf＝－20.81 ppm/oC were obtained at 1170oC/4h. NiNb2O6 along with NiO formed at 1170 to
1300oC/2h sintering,NN. Ni4Nb2O9 phase appeared at 1300oC sintering and Ni4Nb2O9 became major phase at sintering temperature >1300 oC. The optimum density 5.71g/cm3 and shrinkage 13.97% were obtained. εr＝13.23,Qxf＝21,085GHz (10.53GHz),τf＝－13.58 ppm/oC were obtained at 1350oC/2h sintering. With a heating rate and cooling rate of 30oC/min, NN of pure Ni4Nb2O9 could be obtained at 1300oC/2h sintering.

並列關鍵字

Reaction-sintering process ； Microwave dielectric ceramics

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